bytecompiler/BytecodeGenerator.h

   1 /*
   2  * Copyright (C) 2008, 2009 Apple Inc. All rights reserved.
   3  * Copyright (C) 2008 Cameron Zwarich <cwzwarich@uwaterloo.ca>
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  *
   9  * 1.  Redistributions of source code must retain the above copyright
  10  *     notice, this list of conditions and the following disclaimer.
  11  * 2.  Redistributions in binary form must reproduce the above copyright
  12  *     notice, this list of conditions and the following disclaimer in the
  13  *     documentation and/or other materials provided with the distribution.
  14  * 3.  Neither the name of Apple Computer, Inc. ("Apple") nor the names of
  15  *     its contributors may be used to endorse or promote products derived
  16  *     from this software without specific prior written permission.
  17  *
  18  * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY
  19  * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
  20  * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  21  * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY
  22  * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  23  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  24  * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
  25  * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  28  */
  29
  30 #ifndef BytecodeGenerator_h
  31 #define BytecodeGenerator_h
  32
  33 #include "CodeBlock.h"
  34 #include "HashTraits.h"
  35 #include "Instruction.h"
  36 #include "Label.h"
  37 #include "LabelScope.h"
  38 #include "Interpreter.h"
  39 #include "RegisterID.h"
  40 #include "SegmentedVector.h"
  41 #include "SymbolTable.h"
  42 #include "Debugger.h"
  43 #include "Nodes.h"
  44 #include <wtf/PassRefPtr.h>
  45 #include <wtf/Vector.h>
  46
  47 namespace JSC {
  48
  49     class Identifier;
  50     class ScopeChain;
  51     class ScopeNode;
  52
  53     struct FinallyContext {
  54         Label* finallyAddr;
  55         RegisterID* retAddrDst;
  56     };
  57
  58     struct ControlFlowContext {
  59         bool isFinallyBlock;
  60         FinallyContext finallyContext;
  61     };
  62
  63     class BytecodeGenerator {
  64     public:
  65         typedef DeclarationStacks::VarStack VarStack;
  66         typedef DeclarationStacks::FunctionStack FunctionStack;
  67
  68         static void setDumpsGeneratedCode(bool dumpsGeneratedCode);
  69         static bool dumpsGeneratedCode();
  70
  71         BytecodeGenerator(ProgramNode*, const Debugger*, const ScopeChain&, SymbolTable*, ProgramCodeBlock*);
  72         BytecodeGenerator(FunctionBodyNode*, const Debugger*, const ScopeChain&, SymbolTable*, CodeBlock*);
  73         BytecodeGenerator(EvalNode*, const Debugger*, const ScopeChain&, SymbolTable*, EvalCodeBlock*);
  74
  75         JSGlobalData* globalData() const { return m_globalData; }
  76         const CommonIdentifiers& propertyNames() const { return *m_globalData->propertyNames; }
  77
  78         void generate();
  79
  80         // Returns the register corresponding to a local variable, or 0 if no
  81         // such register exists. Registers returned by registerFor do not
  82         // require explicit reference counting.
  83         RegisterID* registerFor(const Identifier&);
  84
  85         // Behaves as registerFor does, but ignores dynamic scope as
  86         // dynamic scope should not interfere with const initialisation
  87         RegisterID* constRegisterFor(const Identifier&);
  88
  89         // Searches the scope chain in an attempt to  statically locate the requested
  90         // property.  Returns false if for any reason the property cannot be safely
  91         // optimised at all.  Otherwise it will return the index and depth of the
  92         // VariableObject that defines the property.  If the property cannot be found
  93         // statically, depth will contain the depth of the scope chain where dynamic
  94         // lookup must begin.
  95         //
  96         // NB: depth does _not_ include the local scope.  eg. a depth of 0 refers
  97         // to the scope containing this codeblock.
  98         bool findScopedProperty(const Identifier&, int& index, size_t& depth, bool forWriting, JSObject*& globalObject);
  99
 100         // Returns the register storing "this"
 101         RegisterID* thisRegister() { return &m_thisRegister; }
 102
 103         bool isLocal(const Identifier&);
 104         bool isLocalConstant(const Identifier&);
 105
 106         // Returns the next available temporary register. Registers returned by
 107         // newTemporary require a modified form of reference counting: any
 108         // register with a refcount of 0 is considered "available", meaning that
 109         // the next instruction may overwrite it.
 110         RegisterID* newTemporary();
 111
 112         RegisterID* highestUsedRegister();
 113
 114         // The same as newTemporary(), but this function returns "suggestion" if
 115         // "suggestion" is a temporary. This function is helpful in situations
 116         // where you've put "suggestion" in a RefPtr, but you'd like to allow
 117         // the next instruction to overwrite it anyway.
 118         RegisterID* newTemporaryOr(RegisterID* suggestion) { return suggestion->isTemporary() ? suggestion : newTemporary(); }
 119
 120         // Functions for handling of dst register
 121
 122         RegisterID* ignoredResult() { return &m_ignoredResultRegister; }
 123
 124         // Returns a place to write intermediate values of an operation
 125         // which reuses dst if it is safe to do so.
 126         RegisterID* tempDestination(RegisterID* dst)
 127         {
 128             return (dst && dst != ignoredResult() && dst->isTemporary()) ? dst : newTemporary();
 129         }
 130
 131         // Returns the place to write the final output of an operation.
 132         RegisterID* finalDestination(RegisterID* originalDst, RegisterID* tempDst = 0)
 133         {
 134             if (originalDst && originalDst != ignoredResult())
 135                 return originalDst;
 136             ASSERT(tempDst != ignoredResult());
 137             if (tempDst && tempDst->isTemporary())
 138                 return tempDst;
 139             return newTemporary();
 140         }
 141
 142         RegisterID* destinationForAssignResult(RegisterID* dst)
 143         {
 144             if (dst && dst != ignoredResult() && m_codeBlock->needsFullScopeChain())
 145                 return dst->isTemporary() ? dst : newTemporary();
 146             return 0;
 147         }
 148
 149         // Moves src to dst if dst is not null and is different from src, otherwise just returns src.
 150         RegisterID* moveToDestinationIfNeeded(RegisterID* dst, RegisterID* src)
 151         {
 152             return dst == ignoredResult() ? 0 : (dst && dst != src) ? emitMove(dst, src) : src;
 153         }
 154
 155         PassRefPtr<LabelScope> newLabelScope(LabelScope::Type, const Identifier* = 0);
 156         PassRefPtr<Label> newLabel();
 157
 158         // The emitNode functions are just syntactic sugar for calling
 159         // Node::emitCode. These functions accept a 0 for the register,
 160         // meaning that the node should allocate a register, or ignoredResult(),
 161         // meaning that the node need not put the result in a register.
 162         // Other emit functions do not accept 0 or ignoredResult().
 163         RegisterID* emitNode(RegisterID* dst, Node* n)
 164         {
 165             // Node::emitCode assumes that dst, if provided, is either a local or a referenced temporary.
 166             ASSERT(!dst || dst == ignoredResult() || !dst->isTemporary() || dst->refCount());
 167             if (!m_codeBlock->numberOfLineInfos() || m_codeBlock->lastLineInfo().lineNumber != n->lineNo()) {
 168                 LineInfo info = { instructions().size(), n->lineNo() };
 169                 m_codeBlock->addLineInfo(info);
 170             }
 171             if (m_emitNodeDepth >= s_maxEmitNodeDepth)
 172                 return emitThrowExpressionTooDeepException();
 173             ++m_emitNodeDepth;
 174             RegisterID* r = n->emitBytecode(*this, dst);
 175             --m_emitNodeDepth;
 176             return r;
 177         }
 178
 179         RegisterID* emitNode(Node* n)
 180         {
 181             return emitNode(0, n);
 182         }
 183
 184         void emitExpressionInfo(unsigned divot, unsigned startOffset, unsigned endOffset)
 185         {
 186             divot -= m_codeBlock->sourceOffset();
 187             if (divot > ExpressionRangeInfo::MaxDivot) {
 188                 // Overflow has occurred, we can only give line number info for errors for this region
 189                 divot = 0;
 190                 startOffset = 0;
 191                 endOffset = 0;
 192             } else if (startOffset > ExpressionRangeInfo::MaxOffset) {
 193                 // If the start offset is out of bounds we clear both offsets
 194                 // so we only get the divot marker.  Error message will have to be reduced
 195                 // to line and column number.
 196                 startOffset = 0;
 197                 endOffset = 0;
 198             } else if (endOffset > ExpressionRangeInfo::MaxOffset) {
 199                 // The end offset is only used for additional context, and is much more likely
 200                 // to overflow (eg. function call arguments) so we are willing to drop it without
 201                 // dropping the rest of the range.
 202                 endOffset = 0;
 203             }
 204
 205             ExpressionRangeInfo info;
 206             info.instructionOffset = instructions().size();
 207             info.divotPoint = divot;
 208             info.startOffset = startOffset;
 209             info.endOffset = endOffset;
 210             m_codeBlock->addExpressionInfo(info);
 211         }
 212
 213         void emitGetByIdExceptionInfo(OpcodeID opcodeID)
 214         {
 215             // Only op_construct and op_instanceof need exception info for
 216             // a preceding op_get_by_id.
 217             ASSERT(opcodeID == op_construct || opcodeID == op_instanceof);
 218             GetByIdExceptionInfo info;
 219             info.bytecodeOffset = instructions().size();
 220             info.isOpConstruct = (opcodeID == op_construct);
 221             m_codeBlock->addGetByIdExceptionInfo(info);
 222         }
 223
 224         ALWAYS_INLINE bool leftHandSideNeedsCopy(bool rightHasAssignments, bool rightIsPure)
 225         {
 226             return (m_codeType != FunctionCode || m_codeBlock->needsFullScopeChain() || rightHasAssignments) && !rightIsPure;
 227         }
 228
 229         ALWAYS_INLINE PassRefPtr<RegisterID> emitNodeForLeftHandSide(ExpressionNode* n, bool rightHasAssignments, bool rightIsPure)
 230         {
 231             if (leftHandSideNeedsCopy(rightHasAssignments, rightIsPure)) {
 232                 PassRefPtr<RegisterID> dst = newTemporary();
 233                 emitNode(dst.get(), n);
 234                 return dst;
 235             }
 236
 237             return PassRefPtr<RegisterID>(emitNode(n));
 238         }
 239
 240         RegisterID* emitLoad(RegisterID* dst, bool);
 241         RegisterID* emitLoad(RegisterID* dst, double);
 242         RegisterID* emitLoad(RegisterID* dst, const Identifier&);
 243         RegisterID* emitLoad(RegisterID* dst, JSValuePtr);
 244         RegisterID* emitUnexpectedLoad(RegisterID* dst, bool);
 245         RegisterID* emitUnexpectedLoad(RegisterID* dst, double);
 246
 247         RegisterID* emitUnaryOp(OpcodeID, RegisterID* dst, RegisterID* src);
 248         RegisterID* emitBinaryOp(OpcodeID, RegisterID* dst, RegisterID* src1, RegisterID* src2, OperandTypes);
 249         RegisterID* emitEqualityOp(OpcodeID, RegisterID* dst, RegisterID* src1, RegisterID* src2);
 250         RegisterID* emitUnaryNoDstOp(OpcodeID, RegisterID* src);
 251
 252         RegisterID* emitNewObject(RegisterID* dst);
 253         RegisterID* emitNewArray(RegisterID* dst, ElementNode*); // stops at first elision
 254
 255         RegisterID* emitNewFunction(RegisterID* dst, FuncDeclNode* func);
 256         RegisterID* emitNewFunctionExpression(RegisterID* dst, FuncExprNode* func);
 257         RegisterID* emitNewRegExp(RegisterID* dst, RegExp* regExp);
 258
 259         RegisterID* emitMove(RegisterID* dst, RegisterID* src);
 260
 261         RegisterID* emitToJSNumber(RegisterID* dst, RegisterID* src) { return emitUnaryOp(op_to_jsnumber, dst, src); }
 262         RegisterID* emitPreInc(RegisterID* srcDst);
 263         RegisterID* emitPreDec(RegisterID* srcDst);
 264         RegisterID* emitPostInc(RegisterID* dst, RegisterID* srcDst);
 265         RegisterID* emitPostDec(RegisterID* dst, RegisterID* srcDst);
 266
 267         RegisterID* emitInstanceOf(RegisterID* dst, RegisterID* value, RegisterID* base, RegisterID* basePrototype);
 268         RegisterID* emitTypeOf(RegisterID* dst, RegisterID* src) { return emitUnaryOp(op_typeof, dst, src); }
 269         RegisterID* emitIn(RegisterID* dst, RegisterID* property, RegisterID* base) { return emitBinaryOp(op_in, dst, property, base, OperandTypes()); }
 270
 271         RegisterID* emitResolve(RegisterID* dst, const Identifier& property);
 272         RegisterID* emitGetScopedVar(RegisterID* dst, size_t skip, int index, JSValuePtr globalObject);
 273         RegisterID* emitPutScopedVar(size_t skip, int index, RegisterID* value, JSValuePtr globalObject);
 274
 275         RegisterID* emitResolveBase(RegisterID* dst, const Identifier& property);
 276         RegisterID* emitResolveWithBase(RegisterID* baseDst, RegisterID* propDst, const Identifier& property);
 277         RegisterID* emitResolveFunction(RegisterID* baseDst, RegisterID* funcDst, const Identifier& property);
 278
 279         RegisterID* emitGetById(RegisterID* dst, RegisterID* base, const Identifier& property);
 280         RegisterID* emitPutById(RegisterID* base, const Identifier& property, RegisterID* value);
 281         RegisterID* emitDeleteById(RegisterID* dst, RegisterID* base, const Identifier&);
 282         RegisterID* emitGetByVal(RegisterID* dst, RegisterID* base, RegisterID* property);
 283         RegisterID* emitPutByVal(RegisterID* base, RegisterID* property, RegisterID* value);
 284         RegisterID* emitDeleteByVal(RegisterID* dst, RegisterID* base, RegisterID* property);
 285         RegisterID* emitPutByIndex(RegisterID* base, unsigned index, RegisterID* value);
 286         RegisterID* emitPutGetter(RegisterID* base, const Identifier& property, RegisterID* value);
 287         RegisterID* emitPutSetter(RegisterID* base, const Identifier& property, RegisterID* value);
 288
 289         RegisterID* emitCall(RegisterID* dst, RegisterID* func, RegisterID* thisRegister, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
 290         RegisterID* emitCallEval(RegisterID* dst, RegisterID* func, RegisterID* thisRegister, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
 291
 292         RegisterID* emitReturn(RegisterID* src);
 293         RegisterID* emitEnd(RegisterID* src) { return emitUnaryNoDstOp(op_end, src); }
 294
 295         RegisterID* emitConstruct(RegisterID* dst, RegisterID* func, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
 296
 297         PassRefPtr<Label> emitLabel(Label*);
 298         PassRefPtr<Label> emitJump(Label* target);
 299         PassRefPtr<Label> emitJumpIfTrue(RegisterID* cond, Label* target);
 300         PassRefPtr<Label> emitJumpIfFalse(RegisterID* cond, Label* target);
 301         PassRefPtr<Label> emitJumpScopes(Label* target, int targetScopeDepth);
 302
 303         PassRefPtr<Label> emitJumpSubroutine(RegisterID* retAddrDst, Label*);
 304         void emitSubroutineReturn(RegisterID* retAddrSrc);
 305
 306         RegisterID* emitGetPropertyNames(RegisterID* dst, RegisterID* base) { return emitUnaryOp(op_get_pnames, dst, base); }
 307         RegisterID* emitNextPropertyName(RegisterID* dst, RegisterID* iter, Label* target);
 308
 309         RegisterID* emitCatch(RegisterID*, Label* start, Label* end);
 310         void emitThrow(RegisterID* exc) { emitUnaryNoDstOp(op_throw, exc); }
 311         RegisterID* emitNewError(RegisterID* dst, ErrorType type, JSValuePtr message);
 312         void emitPushNewScope(RegisterID* dst, Identifier& property, RegisterID* value);
 313
 314         RegisterID* emitPushScope(RegisterID* scope);
 315         void emitPopScope();
 316
 317         void emitDebugHook(DebugHookID, int firstLine, int lastLine);
 318
 319         int scopeDepth() { return m_dynamicScopeDepth + m_finallyDepth; }
 320         bool hasFinaliser() { return m_finallyDepth != 0; }
 321
 322         void pushFinallyContext(Label* target, RegisterID* returnAddrDst);
 323         void popFinallyContext();
 324
 325         LabelScope* breakTarget(const Identifier&);
 326         LabelScope* continueTarget(const Identifier&);
 327
 328         void beginSwitch(RegisterID*, SwitchInfo::SwitchType);
 329         void endSwitch(uint32_t clauseCount, RefPtr<Label>*, ExpressionNode**, Label* defaultLabel, int32_t min, int32_t range);
 330
 331         CodeType codeType() const { return m_codeType; }
 332
 333         void setRegeneratingForExceptionInfo(CodeBlock* originalCodeBlock)
 334         {
 335             m_regeneratingForExceptionInfo = true;
 336             m_codeBlockBeingRegeneratedFrom = originalCodeBlock;
 337         }
 338
 339     private:
 340         void emitOpcode(OpcodeID);
 341         void retrieveLastBinaryOp(int& dstIndex, int& src1Index, int& src2Index);
 342         void retrieveLastUnaryOp(int& dstIndex, int& srcIndex);
 343         void rewindBinaryOp();
 344         void rewindUnaryOp();
 345
 346         PassRefPtr<Label> emitComplexJumpScopes(Label* target, ControlFlowContext* topScope, ControlFlowContext* bottomScope);
 347
 348         struct JSValueHashTraits : HashTraits<JSValueEncodedAsPointer*> {
 349             static void constructDeletedValue(JSValueEncodedAsPointer*& slot) { slot = JSValuePtr::encode(jsImpossibleValue()); }
 350             static bool isDeletedValue(JSValueEncodedAsPointer* value) { return value == JSValuePtr::encode(jsImpossibleValue()); }
 351         };
 352
 353         typedef HashMap<JSValueEncodedAsPointer*, unsigned, PtrHash<JSValueEncodedAsPointer*>, JSValueHashTraits> JSValueMap;
 354
 355         struct IdentifierMapIndexHashTraits {
 356             typedef int TraitType;
 357             typedef IdentifierMapIndexHashTraits StorageTraits;
 358             static int emptyValue() { return std::numeric_limits<int>::max(); }
 359             static const bool emptyValueIsZero = false;
 360             static const bool needsDestruction = false;
 361             static const bool needsRef = false;
 362         };
 363
 364         typedef HashMap<RefPtr<UString::Rep>, int, IdentifierRepHash, HashTraits<RefPtr<UString::Rep> >, IdentifierMapIndexHashTraits> IdentifierMap;
 365         typedef HashMap<double, JSValuePtr> NumberMap;
 366         typedef HashMap<UString::Rep*, JSString*, IdentifierRepHash> IdentifierStringMap;
 367
 368         RegisterID* emitCall(OpcodeID, RegisterID* dst, RegisterID* func, RegisterID* thisRegister, ArgumentsNode*, unsigned divot, unsigned startOffset, unsigned endOffset);
 369
 370         RegisterID* newRegister();
 371
 372         // Returns the RegisterID corresponding to ident.
 373         RegisterID* addVar(const Identifier& ident, bool isConstant)
 374         {
 375             RegisterID* local;
 376             addVar(ident, isConstant, local);
 377             return local;
 378         }
 379         // Returns true if a new RegisterID was added, false if a pre-existing RegisterID was re-used.
 380         bool addVar(const Identifier&, bool isConstant, RegisterID*&);
 381
 382         // Returns the RegisterID corresponding to ident.
 383         RegisterID* addGlobalVar(const Identifier& ident, bool isConstant)
 384         {
 385             RegisterID* local;
 386             addGlobalVar(ident, isConstant, local);
 387             return local;
 388         }
 389         // Returns true if a new RegisterID was added, false if a pre-existing RegisterID was re-used.
 390         bool addGlobalVar(const Identifier&, bool isConstant, RegisterID*&);
 391
 392         RegisterID* addParameter(const Identifier&);
 393
 394         void allocateConstants(size_t);
 395
 396         RegisterID& registerFor(int index)
 397         {
 398             if (index >= 0)
 399                 return m_calleeRegisters[index];
 400
 401             if (index == RegisterFile::OptionalCalleeArguments)
 402                 return m_argumentsRegister;
 403
 404             if (m_parameters.size()) {
 405                 ASSERT(!m_globals.size());
 406                 return m_parameters[index + m_parameters.size() + RegisterFile::CallFrameHeaderSize];
 407             }
 408
 409             return m_globals[-index - 1];
 410         }
 411
 412         unsigned addConstant(FuncDeclNode*);
 413         unsigned addConstant(FuncExprNode*);
 414         unsigned addConstant(const Identifier&);
 415         RegisterID* addConstant(JSValuePtr);
 416         unsigned addUnexpectedConstant(JSValuePtr);
 417         unsigned addRegExp(RegExp*);
 418
 419         Vector<Instruction>& instructions() { return m_codeBlock->instructions(); }
 420         SymbolTable& symbolTable() { return *m_symbolTable; }
 421
 422         bool shouldOptimizeLocals() { return (m_codeType != EvalCode) && !m_dynamicScopeDepth; }
 423         bool canOptimizeNonLocals() { return (m_codeType == FunctionCode) && !m_dynamicScopeDepth && !m_codeBlock->usesEval(); }
 424
 425         RegisterID* emitThrowExpressionTooDeepException();
 426
 427         bool m_shouldEmitDebugHooks;
 428         bool m_shouldEmitProfileHooks;
 429
 430         const ScopeChain* m_scopeChain;
 431         SymbolTable* m_symbolTable;
 432
 433         ScopeNode* m_scopeNode;
 434         CodeBlock* m_codeBlock;
 435
 436         HashSet<RefPtr<UString::Rep>, IdentifierRepHash> m_functions;
 437         RegisterID m_ignoredResultRegister;
 438         RegisterID m_thisRegister;
 439         RegisterID m_argumentsRegister;
 440         int m_activationRegisterIndex;
 441         SegmentedVector<RegisterID, 512> m_calleeRegisters;
 442         SegmentedVector<RegisterID, 512> m_parameters;
 443         SegmentedVector<RegisterID, 512> m_globals;
 444         SegmentedVector<LabelScope, 256> m_labelScopes;
 445         SegmentedVector<Label, 256> m_labels;
 446         RefPtr<RegisterID> m_lastConstant;
 447         int m_finallyDepth;
 448         int m_dynamicScopeDepth;
 449         int m_baseScopeDepth;
 450         CodeType m_codeType;
 451
 452         Vector<ControlFlowContext> m_scopeContextStack;
 453         Vector<SwitchInfo> m_switchContextStack;
 454
 455         int m_nextGlobalIndex;
 456         int m_nextParameterIndex;
 457         int m_nextConstantIndex;
 458
 459         int m_globalVarStorageOffset;
 460
 461         // Constant pool
 462         IdentifierMap m_identifierMap;
 463         JSValueMap m_jsValueMap;
 464         NumberMap m_numberMap;
 465         IdentifierStringMap m_stringMap;
 466
 467         JSGlobalData* m_globalData;
 468
 469         OpcodeID m_lastOpcodeID;
 470
 471         unsigned m_emitNodeDepth;
 472
 473         bool m_regeneratingForExceptionInfo;
 474         CodeBlock* m_codeBlockBeingRegeneratedFrom;
 475
 476         static const unsigned s_maxEmitNodeDepth = 10000;
 477     };
 478
 479 }
 480
 481 #endif // BytecodeGenerator_h